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    Subject[PATCH 4.14 109/178] btrfs: Explicitly handle btrfs_update_root failure
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Nikolay Borisov <nborisov@suse.com>


    [ Upstream commit 9417ebc8a676487c6ec8825f92fb28f7dbeb5f4b ]

    btrfs_udpate_root can fail and it aborts the transaction, the correct
    way to handle an aborted transaction is to explicitly end with
    btrfs_end_transaction. Even now the code is correct since
    btrfs_commit_transaction would handle an aborted transaction but this is
    more of an implementation detail. So let's be explicit in handling
    failure in btrfs_update_root.

    Furthermore btrfs_commit_transaction can also fail and by ignoring it's
    return value we could have left the in-memory copy of the root item in
    an inconsistent state. So capture the error value which allows us to
    correctly revert the RO/RW flags in case of commit failure.

    Signed-off-by: Nikolay Borisov <nborisov@suse.com>
    Signed-off-by: David Sterba <dsterba@suse.com>
    Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    fs/btrfs/ioctl.c | 7 ++++++-
    1 file changed, 6 insertions(+), 1 deletion(-)

    --- a/fs/btrfs/ioctl.c
    +++ b/fs/btrfs/ioctl.c
    @@ -1842,8 +1842,13 @@ static noinline int btrfs_ioctl_subvol_s

    ret = btrfs_update_root(trans, fs_info->tree_root,
    &root->root_key, &root->root_item);
    + if (ret < 0) {
    + btrfs_end_transaction(trans);
    + goto out_reset;
    + }
    +
    + ret = btrfs_commit_transaction(trans);

    - btrfs_commit_transaction(trans);
    out_reset:
    if (ret)
    btrfs_set_root_flags(&root->root_item, root_flags);

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